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Hydrogeological Software

MINEDW

MINEDW is three dimensional finite element groundwater flow software used to simulates open-pit and underground mining for dewatering design and input to slope-stability analysis. Developed from FEMFLOW3D, MINEDW was validated by Sandia National Laboratories in 1998 and has been used at more than 50 mines world wide in diverse hydrogeologic and climatic conditions.

Applications

Prediction of requirements and schedule of dewatering wells and drainage galleries

Environmental Impact Assessment

Drawdown predictions

Assessments of impacts on surface water

Pit-lake infilling simulations

Pore-Pressure Analysis

As an input to ground-stability analysis

Assessments of effectiveness of various pore-pressure reduction schemes

Features

Finite-Element Grid

The grid is specified in terms of triangular prisms and facilitates representation of complex geometries and highly-variable spatial discretization, which is particularly useful for mining applications with complex geologic structures and steep hydraulic gradients.

Progressive Geometry

The elevation of nodes of the finite-element grid can be defined to vary through time. This enables more accurate representation of the underground workings and open pits according to the mine schedules being evaluated.

Saturated/Unsaturated Flow

The finite-element grid can remain fixed through time (with the exception of excavations), and the saturated flow domain can change through time in accordance with changes in the water table, further facilitating representation of the spatial hydrogeologic variability of the groundwater system without additional computational overhead of solving unsaturated flow equations.

Boundary conditions can be represented as specified-head, specified-flux, and internal source-sink terms (each of which can be variant or invariant with time), or as variable-flux boundaries that simulate time-variant fluxes in response to changing boundary heads and an infinite aquifer.

Streams are simulated as river networks of hydraulic compartmentalization and the model simulates river depletions and additions from exchange with groundwater.

Evaporation/Evapotranspiration

Loss of water from bare/vegetated soils can be simulated and is proportional to the distance between the ground surface and water table, with maximum evaporation rate and extinction depth as constraints.

Pit Lakes

Excavation and pit-lake infilling of multiple pits can be simulated within the same model domain and their respective mining schedules represented simultaneously. The model also provides node-bynode fluxes into/out of the pit lake, evaporation and precipitation on the lake surface, and predictions of lake stages as a function of time, which can readily be used to predict detailed hydrodynamic and geochemical pit-lake conditions and to predict pit-wall seepage during mining.

Time-Variant Conductivity

Can be used to represent the zone of relaxation around excavations, backfilling operations, longwall and room-and-pillar coal mining, freeze-thaw conditions, or other scenarios where hydraulic conductivity may change during the simulation period.

Numerically Stable

Due in part to the finite element grid and the numerical methods applied in the model, MINEDW is typically very stable numerically. This is particularly important in cases where there is a high degree of hydraulic compartmentalization with steep hydraulic gradients.